i(3)so3-galactosylceramide and Wallerian-Degeneration

Sulfatide synthesis from sulfate is much greater in the peripheral nerves of the Trembler mouse. After nerve transection, during Wallerian degeneration, this synthesis rate drops down very rapidly in both normal and Trembler mice. Twenty-four hours after permanent transection, the rate of synthesis is reduced by 80% in the mutant and 50% in the normal mouse. Four days after transection, the synthesis rate in the Trembler is only 9% of that observed in intact nerves, and 21% of that in the intact nerves of normal animals. After 5 d the synthesis remains constant. Thus, enhanced synthesis of sulfatides in the Trembler mouse is probably not caused by Wallerian degeneration. After crush of the sciatic nerve, the synthesis rate decreases very rapidly in the normal mouse as it does after permanent transection. But during regeneration, from the 7th day, it rises dramatically and 14 d after crush, a 2.5-fold increase in the synthesis rate is observed, compared to that in the contralateral control nerve. This synthesis rate returns to normal 1 mo after crush. In the Trembler, the synthesis decreases for 2 d after crush and increases from then on, eventually reaching the value of the contralateral control Trembler nerve within 2 mo. In the mutant there is no prominent peak of sulfatide synthesis during regeneration.

Topics: Animals; Mice; Mice, Neurologic Mutants; Myelin Sheath; Nerve Crush; Nerve Degeneration; Sciatic Nerve; Sulfates; Sulfoglycosphingolipids; Time Factors; Wallerian Degeneration

The structural alterations of monogalactosylceramides in peripheral nerve were investigated during development, nerve fiber degeneration and regeneration. During early development, hydroxy cerebrosides and sulfatides were the main constituents of the monogalactosylceramides of immature rat sciatic endoneurium. The ratio of hydroxy to nonhydroxy cerebrosides decreased rapidly as myelination proceeded but remained fairly constant throughout adulthood. More than 50% of the adult content of endoneurial monogalactosylceramides was achieved before 21 days of age. The long-chain nonhydroxy fatty acids (above C21) had increased from under 20% to over 80% by day 20, while 24h:0 (h, hydroxy) had already reached approximately 50% of hydroxy cerebrosides by day 12. These results suggest that the biosynthesis of endoneurial monogalactosylceramides and fatty acid elongation take place preferentially at the time when peripheral nerve is undergoing active myelination. During Wallerian degeneration, the maximum decrease of monogalactosylceramides was associated temporally with axonal degeneration and demyelination and particularly with myelin conversion to sudanophilic lipids. By the time that nerve fiber regeneration was well established, both the cerebroside and sulfatide contents had returned to near control values. Cerebrosides and long-chain fatty acids (above C21) appear to be the most sensitive to fiber degeneration while fatty acid elongation is selectively increased during nerve regeneration.

Topics: Animals; Cerebrosides; Chemical Phenomena; Chemistry; Chromatography, Thin Layer; Galactosylceramides; Male; Nerve Degeneration; Peripheral Nerves; Rats; Rats, Inbred Strains; Sulfoglycosphingolipids; Wallerian Degeneration

This report described a new method for the microanalysis of sphingolipids and its application for the characterization of cerebrosides and sulfatides in multiple sclerosis brain and rat sciatic nerves undergoing Wallerian degeneration. Tissue was extracted with isopropanol/hexane (20:78), and the total lipids obtained were subjected to benzoylation-desulfation. A portion of this was directly analyzed by silica-column high performance liquid chromatography for the determination of nonhydroxycerebroside, hydroxycerebroside, nonhydroxysulfatide, and hydroxysulfatide. Another portion was fractionated by thin-layer chromatography, and the spots corresponding to the sphingolipid derivatives were eluted. The material from each spot was analyzed by reverse phase high performance liquid chromatography for its homolog composition. With this new procedure the concentrations and homolog compositions of cerebrosides and sulfatides were measured in plaque, periplaque, and normal-appearing white matter from brains of multiple sclerosis patients and Wallerian degenerated rat sciatic nerves distal to the nerve transection. One piece of plaque studied contained only 1.86, 2.76, 0.60, and 0.45 nmol of nonhydroxycerebroside, hydroxycerebroside, nonhydroxysulfatide and hydroxysulfatide/mg of protein, respectively. These concentrations are less than 1% of those found in normal white matter. Periplaques were found to contain concentrations of these sphingolipids between those of plaque and normal white matter. The levels of these sphingolipids in degenerative nerves were 10-20% below normal the third day after the nerve was severed and about 70% below normal after 10 days. The rate of decrease lessened from ten days to 55 days. The homolog compositions of these sphingolipids in both multiple sclerosis brain and degenerating nerves were similar to those in the control. The implications of these findings and the advantages of this new analytical method are discussed.

Topics: Adult; Animals; Brain; Cerebrosides; Chromatography, High Pressure Liquid; Humans; Lipid Metabolism; Male; Multiple Sclerosis; Nerve Degeneration; Rats; Rats, Inbred Strains; Sciatic Nerve; Sulfoglycosphingolipids; Wallerian Degeneration